The present invention relates to a valve. In particular, the present invention relates to a valve arrange to prevent the discharge of water from a water filter when the discharged water would otherwise be contaminated above a predetermined proportion of hydrocarbons. Particular embodiments of the present invention relate to a water filter valve arranged to restrict the flow of hydrocarbon based fuels, such as diesel and biodiesel. Embodiments of the present invention may form part of a water filter for removing hydrocarbons and other contaminants from water separated from fuel in a fuel filter within a liquid fuel supply system.
Fuel supply systems, and in particular vehicle fuel systems generally comprise at least one fuel filter to remove water and other contaminants from the fuel. For medium and heavy duty trucks, there may be multiple fuel filters, to progressively filter water, large particulate contaminants and fine particles from the fuel supply. It is generally necessary to continuously or periodically remove the separated water from the fuel filter in order to prevent water passing through the filter element into the fuel system and reaching the engine injector nozzles. Filtering may be performed either on the pressure side (that is, downstream of the low pressure fuel pump) or on the suction side (upstream of the low pressure fuel pump). The low pressure fuel pump is positioned upstream of the main fuel pump.
The collected water may be drained manually, semi-automatically or fully automatically, The water may either be collected in a separate receptacle or allowed to drain away. For manual and semi-automatic water drains a water sensor within a fuel filter is arranged to detect when the volume of water exceeds a predetermined level. The operator is then alerted, for instance by illuminating a warning light in the vehicle cabin. Semi-automatic an fully automatic fuel drain valves operate using a solenoid valve, which may be remotely operated by the vehicle operator in response to a warning signal in the vehicle cabin or triggered automatically. Solenoid fuel drain valves are electrically operated. The solenoid cycle (that is, the opening and closing of the solenoid valve), and hence the amount of released water, is controlled by an Engine Control Unit (ECU).
Regardless of the type of water drain, fuel may be inadvertently released along with the water, which unless collected and disposed of correctly is a source of pollution. Furthermore, even if pure fuel is not released, the collected water can contain large amounts, for instance 100-1400 ppm or more, of dispersed hydrocarbons, which are environmentally hazardous substances. In order to comply with European Directive 2000/60/EC relating to water pollution, the amount of hydrocarbons in discharged water must be limited. The term “hydrocarbons” is intended herein to include all petroleum based hydrocarbons in a range of C7 to C40 hydrocarbon chains. Limits for hydrocarbon content are set by each individual European country. The hydrocarbon content limits can be dictated by vehicle or engine manufacturers to their fuel system suppliers. The limits for hydrocarbons in discharged water can be as low as 2 ppm. Measurement of the volume of hydrocarbons in discharged water may be performed according to ISO 9377-2. If the amount of hydrocarbons in the collected water exceeds the set limit then the contaminated water must be collected and disposed of under controlled conditions. If the vehicle is not equipped with a storage tank for the drained water, when water within the filter collection bowl builds up beyond a predetermined level and requires draining the vehicle operator is supposed to stop in a depot and collect the drained water into a suitable vessel to allow the water to be disposed of in a controlled manner. However, typically the vehicle operator simply stops the vehicle where convenient and drains the contaminated water onto the road. The drained water is a source of pollution and is illegal. Furthermore, if pure diesel is spilt onto the road then this could cause accidents due to vehicles slipping on the spilt diesel.
It is known to provide filters to reduce the concentration of hydrocarbons in discharged water. For instance, a water filter may contain a material arranged to absorb hydrocarbons such as activated carbon or activated charcoal. The extremely large surface area (up to 1500 m2·g−1) of activated charcoal allows for efficient filtration. Toxins such as hydrocarbons build up on the surface of the charcoal due to Van-der-Waals forces. The skilled person will be aware of other suitable materials for absorbing or adsorbing hydrocarbons.
A potential problem associated with water filters for removing hydrocarbons from water is that they may be positioned within the engine bay and due to their inaccessibility it can be difficult to monitor when a filter or filter cartridge requires replacement. Furthermore, the proportion of water in a fuel supply cannot be accurately predicted and so it is necessary to provide a larger water filter than may be strictly required in order to ensure that the filter continues to function until the vehicle is next serviced.
U.S. Pat. No. 7,297,267-B2, which is assigned to Parker-Hannifin Corporation, discloses an oil-sorbing filter element for removing oil from water, for instance from bilge water from a boat. The filter element is generally cylindrical and comprises a permeable outer wall and a permeable tubular core. Between the outer wall and the core there is a filter media or optionally first and second layers of the same or differing filter media surrounding the core. In use the filter element is positioned within a filter housing such that water passes into the housing surrounding the outer wall and permeates through the outer wall into the filter element. The water then passes through the filter media and permeates through the core to exit the filter element via the tubular core. The flow path may also be reversed. The construction of the outer wall, core and filter media is intended to address problems associated with known water filters, which use fibrous or loose fill adsorbent mediums. Specifically, the filter element is intended to address the problems of filter media settling or channelling caused by the flow of the treatment stream. Settling and channelling can shorten the service life of the filter as the water being treated bypasses portions of the filter media that are not yet exhausted.
The filter media disclosed in U.S. Pat. No. 7,297,267-B2 preferably comprises an oleophilic polymeric material. The material is broadly defined as an oil-absorbing thermoplastic elastomer. The terms “oleophilic” and “oil-adsorbing” are defined as meaning that the material has an affinity to hydrocarbons or sorbs hydrocarbons and other sorbable materials, for instance diesel. More particularly, the material may be a styrenic mid-block (A-B-A) copolymer, with the mid-block being a saturated elastomer, for instance styrene-ethylene/butylene-styrene (SEBS) or styrene-ethylene/propylene-styrene (SEPS) or an unsaturated elastomer for instance styrene-butadiene-styrene (SBS) or styrene-isoprene-styrene (SIS). A particularly preferred material is a linear mid-block SEBS copolymer (30 wt % styrene) which is marketed under the name Kraton® G1652 by Kraton Polymers, Houston, Tex., US. A range of alternative materials is also disclosed.
PCT Patent Application PCT/GB2010/050996, which is assigned to Parker Hannifin (UK) Limited, discloses a range of water filters for use in combination with fuel filter water separators. The water filters include a filter indicator arranged to restrict the flow of water through the water filter when the water filter is approaching exhaustion.